Cortisol as an indicator of dopaminergic effects on nicotine craving

Sudanese Toombak smokeless tobacco users harbour significantly altered long-term cortisol body production

The Sudanese, in particular its male population, are known to utilise a smokeless tobacco product (Toombak) which is placed in the oral cavity and can be replaced several times a day. Toombak has been shown to harm human health and is highly addictive. The effect on body cortisol response over a retrospective period in users of this product has not been previously explored. In addition, psycho-dependency scores of Toombak users have not been analysed. In this study, 37 male subjects, age 18-45 years were recruited, of which 18 were non-users of Toombak and 19 were Toombak users. One hair sample was collected from each user and non-user of Toombak. Each hair sample (n=37) was placed in a pre-prepared long piece of foil with two labels on either side marked: 'scalp-side' and 'distant-side'. Cortisol was extracted by mincing 10 mg of 'scalp-side' hair, not exceeding 3 cm, with methanol addition, incubation, and sonication. Cortisol was measured using the enzyme-linked immunosorbent assay kit (Enzo Life Sciences, UK). The amount of hair cortisol in the samples was determined using spectrophotometry at wavelength 405 nm measured in pg/ml and visualised with a four parametric logistic curve. Toombak users were further asked to complete the Fagerstrom Test for Nicotine Dependence-Smokeless Tobacco questionnaire (FTND-ST) comprising of six questions. Scores of > 5 indicated a significant dependence, while a score of < 4 marked low to moderate dependence. The mean concentration of hair cortisol in Toombak users (9.7 pg/ml) was significantly lower (p=0.023) compared to non-users (19.4 pg/ml), with total concentrations ranging from 2.1 to 55.6 pg/ml. FTND-ST scores ranged from 4 to 9, with high levels of psycho-dependency (score > 5) and nicotine tolerance found in 85 % of Toombak users. Cortisol body release in Sudanese smokeless tobacco users was found to be significantly altered. While low cortisol levels do lead to anxiolytic effects, in the long-term, this can allow for increased susceptibility to low cortisol-associated diseases.

Different levels of brain-derived neurotrophic factor and cortisol in healthy heavy smokers

Studies suggest that brain-derived neurotrophic factor (BDNF) and the hypothalamic-pituitary-adrenal (HPA) axis modulate dopaminergic activity in response to nicotine and that the concentrations of BDNF and cortisol seem to be dependent on the amount and duration of smoking. Therefore, we investigated BDNF and cortisol levels in smokers ranked by daily cigarette consumption. Twenty-seven adult males (13 non-smokers and 14 smokers) participated in the study. The smokers were divided in two groups: light (n=7) and heavy smokers (n=7). Anthropometric parameters and age were paired between the groups, and plasma BDNF and salivary cortisol levels were measured. Saliva samples were collected on awakening, 30 min after awakening, at 10:00 and 12:00 am, 5:00 and 10:00 pm. Additionally, cotinine serum levels were measured in smokers. Heavy smokers had higher mean values of BDNF compared to the control group (P=0.01), whereas no difference was observed in light smokers. Moreover, heavy smokers presented lower cortisol levels in the last collection (10:00 pm) than the control group (P=0.02) and presented statically higher values of cotinine than the light smokers (P=0.002). In conclusion, changes in BDNF and cortisol levels (10:00 pm) appear to be dependent on heavy cigarette smoking and can be involved in activation and in the relationship between the mesolimbic system and the HPA axis.

Exercise intervention as a protective modulator against metabolic disorders in cigarette smokers

[Purpose] assess the impact of exercise intensity on desire to smoke, serum cotinine, stress hormones, total antioxidant capacity, and oxidative free radicals as potential markers of cardiopulmonary metabolic disorders were measured.in cigarette smokers. [Subjects and Methods] The participants (150 randomly selected healthy men, aged 18–55 years) were classified into 4 smoking groups: control (non-smokers; N= 30); mild (N = 33); moderate (N = 42), and heavy (N = 45). The participants were assigned to either moderate (8 weeks) or short-term (20–45 min) exercise training. The desire to smoke, Mood and Physical Symptoms Scale, and Subjective Exercise Experiences Scale scores, cotinine, stress hormones (cortisol and testosterone), free radicals (malondialdehyde, nitric oxide), and total antioxidant capacity were evaluated. [Results] Significant increases in serum cotinine, cortisol, testosterone, nitric oxide, and malondialdehyde levels and a reduction in total antioxidant capacity activity were observed in all smoker groups; heavy smokers showed a higher change in metabolites. In all smoker groups, both short and moderate- intensity exercises significantly reduce cotinine, cortisol, testosterone, and malondialdehyde and increased nitric oxide levels and total antioxidant capacity activity; further, the desire to smoke, Mood and Physical Symptoms Scale, and Subjective Exercise Experiences Scale scores were reduced. This supports the ability of exercise to increase nitric oxide bioavailability, enhance of blood vessels function and ultimately decrease the incidence of cardiopulmonary disorders. [Conclusion] Exercise interventions with varying intensities may be used as nicotine replacement therapy or protective aids against smoking-related cardiopulmonary disorders.

A randomised placebo-controlled trial of oral hydrocortisone for treating tobacco withdrawal symptoms

RATIONALE

Many smokers experience a decline in cortisol to sub-normal levels during the first days of smoking cessation. A greater decline in cortisol is associated with more intense cigarette withdrawal symptoms, urge to smoke and relapse to smoking. Findings from an uncontrolled study suggest that glucocorticoids could ameliorate cigarette withdrawal.

OBJECTIVES

We investigated whether taking oral hydrocortisone would reduce withdrawal symptoms and the desire to smoke on the first day of temporary smoking abstinence compared with placebo.

METHODS

Using a double-blind within-subject randomised crossover design, 48 smokers took a single dose of 40 mg hydrocortisone, 20 mg hydrocortisone or placebo following overnight smoking abstinence. Abstinence was maintained through the afternoon, and withdrawal symptoms and the desire to smoke were rated across the morning. Salivary cortisol was assessed in the afternoon prior to abstinence (baseline) and while abstinent after each treatment.

RESULTS

There was a significant dose-response relation between dose of hydrocortisone and reduction in depression and anxiety ratings while abstinent, but there were no other statistically significant associations with dose. Overall, the decline in cortisol following smoking cessation (placebo only) was not significant. Cortisol level on the afternoon of smoking abstinence was not significantly associated with symptom ratings.

CONCLUSIONS

Supplements of hydrocortisone do not reduce the desire to smoke but may ameliorate withdrawal-related depression and anxiety, although the clinical benefit is slight.

Repetitive transcranial magnetic stimulation reduces cortisol concentrations in bulimic disorders

BACKGROUND

In people with bulimic eating disorders, exposure to high-calorie foods can result in increases in food craving, raised subjective stress and salivary cortisol concentrations. This cue-induced food craving can be reduced by repetitive transcranial magnetic stimulation (rTMS). We investigated whether rTMS has a similar effect on salivary cortisol concentrations, a measure of hypothalamic-pituitary-adrenal axis (HPAA) activity.

METHOD

We enrolled twenty-two female participants who took part in a double-blind randomized sham-controlled trial on the effects of rTMS on food craving. Per group, eleven participants were randomized to the real or sham rTMS condition. The intervention consisted of one session of high-frequency rTMS delivered to the left dorsolateral prefrontal cortex (DLPFC). Salivary cortisol concentrations were assessed at four time points throughout the 90-min trial. To investigate differences in post-rTMS concentrations between the real and sham rTMS groups, a random-effects model including the pre-rTMS cortisol concentrations as covariates was used.

RESULTS

Salivary cortisol concentrations following real rTMS were significantly lower compared with those following sham rTMS. In this sample, there was also a trend for real rTMS to reduce food craving more than sham rTMS.

CONCLUSIONS

These results suggest that rTMS applied to the left DLPFC alters HPAA activity in people with a bulimic disorder.

Blunted opiate modulation of prolactin response in smoking men and women

Endogenous opioids are integral in modulating drug reward, but it is believed that these may act through several mechanisms including hypothalamic-pituitary-adrenocortical (HPA) and dopamine pathways. This study was developed to examine how nicotine dependence alters endogenous opioid regulation of prolactin response, a peripheral marker of dopaminergic activity. Smokers and nonsmokers completed two sessions during which placebo or 50mg of naltrexone was administered, using a double-blind, counterbalanced design. Blood samples and mood measures were obtained during a resting absorption period, after exposure to two noxious stimuli (cold pressor and thermal pain), and during an extended recovery period. Opioid blockade increased prolactin response, indicating an inhibitory effect of the endogenous opioid system on prolactin, possibly mediated by reduced stimulatory effects of dopamine on this hormone. These responses were attenuated in smokers relative to nonsmokers. There was also a gender disparity in prolactin response, with women showing a stronger response to endogenous opioid modification than men regardless of smoking status. The attenuated effects of opioid blockade may reflect dysregulated opiodergic and dopaminergic effects. Results extend previous reports showing blunted opioid regulation of the HPA response in dependent smokers.

BclI glucocorticoid receptor polymorphism and smoking in the general population

We studied the hypothesis that the BclI polymorphism of the glucocorticoid receptor gene is associated with an increased probability of being a (heavy) smoker and a decreased ability to quit smoking. The study cohort consisted of all subjects in the Rotterdam Study, a Dutch population-based cohort of people aged 55 years and older, for whom BclI genotyping and smoking status at baseline were available. In prospective analyses, the smoking status was reassessed during three additional examination rounds. Logistic regression analysis was used to study the association between BclI polymorphism and being a smoker or a heavy smoker at baseline. Furthermore, the relationship between BclI polymorphism and incident smoking cessation was tested with Cox proportional hazards analysis within those who smoked at baseline. In total, 6358 subjects were included in the study. The presence of a G-allele was not associated with current smoking at baseline [odds ratio (OR) = 0.96, 95%confidence interval (CI): 0.85-1.09] or with the incidence of smoking cessation during follow-up [hazard ratio (HR) = 0.98, 95%CI: 0.80-1.19]. Within current smokers, having a G-allele was not significantly associated with the risk of being a heavy smoker when measured by pack-years smoked (OR = 1.07, 95%CI: 0.85-1.35) or daily consumption of tobacco (OR = 1.10, 95%CI: 0.88-1.37). We were not able to replicate the earlier findings indicating that the proportion of current smokers is lower among carriers of the CC-genotype of the BclI glucocorticoid receptor. Furthermore, the BclI glucocorticoid receptor polymorphism did not predict the incidence of smoking cessation in the general elderly population.

Induction of tyrosine hydroxylase mRNA by nicotine in rat midbrain is inhibited by mifepristone

Repeated nicotine administration induces tyrosine hydroxylase (TH) mRNA in rat midbrain. In this study we investigate the mechanisms responsible for this response using two models of midbrain dopamine neurons, rat ventral midbrain slice explant cultures and mouse MN9D cells. In both models nicotine stimulates TH gene transcription rate in a dose-dependent manner. However, this stimulation is short-lived, lasting for 1 h, but less than 3 h, and is not sufficient to induce TH mRNA or TH protein. Nicotine elevates circulating glucocorticoids, which induce TH expression in some model systems. We tested the hypothesis that the effect of nicotine on midbrain TH mRNA is mediated by the glucocorticoid receptor. When rats are administered the glucocorticoid receptor antagonist mifepristone, the induction of TH mRNA by nicotine in both substantia nigra and ventral tegmentum is inhibited. Furthermore, the glucocorticoid receptor agonist dexamethasone stimulates TH gene transcription for sustained periods of time in both midbrain slices and MN9D cells, leading to induction of TH mRNA and TH protein. Our results are consistent with the hypothesis that nicotine induces TH mRNA in midbrain by elevating glucocorticoids, which then act on glucocorticoid receptors in dopamine neurons leading to transcriptional activation of the TH gene.

Reduction in cortisol after smoking cessation among users of nicotine patches

OBJECTIVE

Cortisol has been shown to decline after stopping smoking and this decline has been associated with smoking relapse and with reports of increased withdrawal severity and distress. We examined whether a decrease in cortisol is evident in smokers trying to quit using nicotine patches and whether cortisol is related to withdrawal symptoms, smoking urges, subjective stress, nicotine dependence, and smoking relapse.

METHODS

Among 112 smokers trying to quit using 15-mg patches, salivary cortisol and reports of stress, withdrawal, and urges were measured before quitting smoking and up to 6 weeks of abstinence among abstinent smokers using 15-mg nicotine patches. Thirty participants both remained abstinent and provided cortisol samples at all measurement times.

RESULTS

Relative to preabstinence, there was a significant decline in cortisol after abstinence of 1 day, and after 1, 2, and 6 weeks (p < .05). The decline in cortisol on the first day of abstinence was positively associated with reported cigarette consumption (p < .01) and tended (nonsignificant) to be associated with smoking relapse at 6 weeks (p = .07). A lower absolute level of cortisol, but not the change in cortisol, on the first day of abstinence was significantly associated with increased reports of urges, withdrawal symptoms, and stress (p < .05), independently of reported cigarette consumption.

CONCLUSIONS

Smokers using 15-mg nicotine patches are likely to experience a decline in cortisol on stopping smoking. This decline is likely to be greater among heavier smokers and may predict relapse to smoking. Those with lower cortisol after cessation may experience increased withdrawal symptoms, urges to smoke, and subjective stress.

Psychobiological Theories of Smoking and Smoking Motivation

Abstract. Theories of smoking have been developed about the conditions and causes of smoking as well as for explaining its maintenance. Moreover, factors of smoking motivation have been identified, which describe incentives to smoke and types of smoking behavior. The most frequently reported motives are psychosocial smoking, sensorimotor smoking, indulgent smoking, stimulation smoking, sedation smoking, dependent smoking, and automatic smoking. In the first phase after the start of smoking, psychosocial smoking is the dominating motive, which is best represented by theories of social psychology. Sensorimotor smoking may be best explained by theories of classical and operant conditioning. Indulgent smoking (= smoking for pleasure) may be explained by neurochemical theories and by the neurobiological theories of dependence emphasizing nicotine-induced activation of mesolimbic dopaminergic reinforcement. Stimulation smoking and sedation smoking are related to arousal models. Moreover, sedation smoking is also explained by aspects of reducing negative affect (as claimed by theories of affect regulation) and by biochemical theories emphasizing serotonergic mechanisms in modulating anxiety as well as by theories of dependence. Dependent smoking, which is mostly based on negative reinforcement (suppression of withdrawal symptoms) may be explained by neurochemical theories as well as by neurobiological theories of psychological and physical dependence explaining blunted dopaminergic and serotonergic responsivity as due to desensitization of respective receptors. Also automatic smoking may be explained by processes of habit learning and neurobiological theories of dependence. Finally, personality theories have been applied to all of these smoking motives.